Method of treating cotton



Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE No Drawing. Application July 15, 1935 Serial No. 31,443

mersion in caustic of mercerizing strength. I

have further found that partial effects of mer- 5 cerizationmay be' imparted to such uncoiled fibers by treatment thereof with caustic of less than mercerizing strength. The effect of the caustic in swelling, strengthening and lusterizing uncoiled fibers varies with the strengthof caustic 2 and duration of immersion therein of the fibers. as contrasted with the abrupt change in the effect on normal coiled fibers when treated, under tension, with caustic of mercerizing strength instead of with more dilute caustic.

- 25 I have further found that uncoiling of the axial spiral twist of the fiat ribbon-like fibers of cotton, with their natural, water repellent waxes and gums adhering thereto, may be eifected by treatment thereof with ammonia, either in the pres- 30 ence or absence of other deguniming agents, and that such ammonia treatment further effectively. degums the fibers and prevents the'conversion thereof into oxycellulose by the concurrent or subsequent treatment of such fibers with caustic.

35 ,Such of my discoveries as are applicable to a particular type of fiber may be utilized as concurrent steps or consecutive steps in the treatment of such fiber, and, when the steps are utilized consecutively, the sequence in which such 40 steps are used are susceptible of considerable variation.

When the steps are utilized concurrently some or all of the reagents employed may be advantageousiy' mixed together before wetting, or in 45 SOlutlOll. q

The fibers may be treated in their raw or unspun state or in the form of bats, slivers, yarns, or in fabricated form such, as woven, knitted or felted fabrics.

5 In the treatment of fibers, the ammonia is preferably utilized as a dilute aqueous solution,

which may be diluted from the aqua-ammonia of commerce or formed by the introduction of anhydrous gas liberated from ammonium salts 55 by reaction of caustic.

' 4 Claims. (01. 8-20) Where the ammoniacal treatment is given in an open vessel, jig or the like, the temperature of the bath is preferably kept at about 140 F. to avoid excessive loss of ammonia, but when the treatment is given in certain forms of enclosed kiers it, 5 may be necessary to operate at a temperature of approximately 228 and a pressure of from 10 to pounds to secure adequate circulation of :the solution through the goods.

The ammoniacal effect on cottonfiber is ap- 10 parent not only by the visible uncoiling and untwisting of the fiber, but is further evidenced by the fact that ammoniacally treated cotton fiber, after thoroughly washing and drying, becomes negatively charged with electricity upon rubbing 15 on glass and will also respond tosuch dyes as are commonly used with nitrogen containing fibers.

' The characteristic features of my invention will further appear from the following illustrative examples, but it will be understood that such examples are by way of illustration only and that the details of methods embodyingthe presence of my invention may be widely varied. In a preferred commercial treatment, in accordance with my invention,' of a broadcloth woven from American peeler cotton and of a weight of say four yards to the pound, the fabric, after the usual singeing and de-starching treatment, may bekier boiled for approximately ten hours in a dilute ammoniacal solution containing minimized by covering the kier. A suitable, but

by no means necessary, temperature for a kier operated on a closed system is approximately 228 whereas a suitable, but'by no means necessary, temperature for a kier operated on an open system is approximately 140'? F. v

. The duration of the kier boil is largely dependent upon the efilclency of the circulation of the kier and the weight of the fabric, but should be continued until the fibers are uncoiled and to a large degree untwisted and the goods are well bottomed.

When the ammoniacal treatment is completed, the goods are well washed in the kier. There is then introduced into the kier an aqueous solution 56 a ew containing approximately 1%".-of sodium perborate, based zomthe weight ofeithe goods.

Thissolution is.-circulated and the: temperature gradually increased by steps, first to- F. at which it is maintained for approximately threequarters of amhour, and thereafter to F. at which thestemperatureis maintained until complete bleachriis effected.

The goods.= are.-again thoroughly washed in the kier, then'washed in a continuous rope washer, soured in aacontinuous rope washer, rewashed in a continuous, rope washer, and then passed through amercerizing bath off caustic soda at a temperature-not exceeding 100 and preferably not less than 70 F., at a strength of caustic of from 40? Twaddell to 56 Twad'dell. ll'he mercerization may be effected in a continuous rope washer or.a: usual type .of fabric pre-shrinklng machine-since the fullmercerizi'ng effect is secured byg myi improvements without the necessity fontensi'on, although, if; desired, the usual merceri'zing; machine. applying tension may be used.

By thi'ss treatment, fabricw woven from Ameri can peelen-cotton may be:- given the lustre, sheen, coverage, and strength and the general appearanceofi a; fabric woven; from. much higher grade cotton. and mercerized previous processes.

Any other oxidizing agent suitable for use in an kien, such, for instance, as sodium peroxide or? hydrogen peroxide,, or: a. mixture thereof, may.

be substituted for the sodium perborate in the, foregoing illustration.

Where complete mercerization is not required,. certainof the advantages of my invention may be obtained by treatment with caustic of'less than mercerizing strength, which will improve the cover, handle and feel and efiect the, pre-shrinking of the fabrics This treatment with caustic of less than mercerizing strength may be effected as a separate step substituted for the mercer- -izing step, or may be effected by introducing caustic in low .concentration into the ammonia kier boil. When used in the kier boil, the caustic is preferably used in an amount; approximating 1 by weight of the ammoniacal solution. When the fibers are uncoiled as a result of the ammoniacal treatment, the action of dilute caustic thereon progressively improves the strength.

cover and handle of thegoods with increases in the caustlc concentration and when the caustic concentration is increased progressively above 18 Twaddell the luster is gradually increased. until the full luster of mercerization is attained at mercerizing strength of the caustic. Under special conditions it may be desirable to give the ammoniacal and cold caustic treatments without the oxidizing treatment, or a combined ammoniacal and hot'caustlc treatment may be given to degum and uncoil the fibers and to improve the coverage of the fabric. p

In some instances it is preferable that the ammoniacal treatment, the oxidizing treatment and the cold. caustic treatment should be performed as separate; and distinct steps consecutively or indispersed with other standard treating operations.

Unspunfibers may be, treated similarly to the treatment given. woven fabrics, and spun fibers may be subjected to the several steps concurrently or sequentially; preferably by forcing the solutions. or.- combined solution through yarn packages: by; the. use of a package machine of the Franklin type or the Overmeyer type. When mercerizatiom off yarns in packages is effected in accordance with my process, by circulating caustic of mercerizing. strength through yarn packages after' the ammoniacal treatment of such packages, the yarn is given the same lustre and strength that is given to yarn by usual mercerization of? a warp rope under tension. Such result; is. efiected without substantial tensiom or contraction offthe yarn sumciently to prevent circulation of the liquid through the package.-

By efiecting mercerization in accordance with my. invention without tension, there is" avoided the stretching of yarns up to or beyond; their elastic; limits such as occurs in ordinary/ mercerization. and fabrics may be produced. inwhich the increase in lustre and strength due-ta mercerizationis in the same proportionforxbrith the weft. yarns and the warp yarns.

Having described my invention, I;clai'nn:

l- The method of treating cotton. fibers containing natural waxes or gums which includes subjecting such fibers to the action of hot aqua ammonia until the axial spiral twist. of the flat ribbon-like cells of such fibers: uncoiJ; and the gums or waxes are softened.

2 In the treatment of cotton. fibers as set forth in claim 1, the step which consists in subjecting the uncoiled fibers to the action of caustic.

3. In the treatment of cotton fibers as set forth in claim 1,, the step which consists in subjecting the uncoiled fibers to the action of caustic. of less mercerizing strength.

4. In the treatment of cotton fibers as set forth in claim 1, the step which'consists of subjecting the uncoiled fibers to the action of caustic without tension.

WILLIAM BEACH PRA'I'IY. 

